The A-10 Thunderbolt II is an American single-seat, twin-engine, straight-wing jet aircraft developed by Fairchild-Republic in the early 1970s. The A-10 was designed for a United States Air Force requirement to provide close air support (CAS) for ground forces by attacking tanks, armored vehicles, and other ground targets with a limited air interdiction capability. It is the first U.S. Air Force aircraft designed exclusively for close air support.

The A-10 Thunderbolt was designed around the GAU-8 Avenger, a heavy automatic cannon which forms the aircraft’s primary armament. The aircraft’s hull incorporates over 1,200 pounds (540 kg) of armor and was designed with survivability as a priority, with protective measures in place which enable the aircraft to continue flying even after taking significant damage.

The A-10’s official name comes from the Republic P-47 Thunderbolt of World War II, a fighter that was particularly effective at close air support. The A-10 Thunderbolt is more commonly known by its nickname “Warthog” or simply “Hog”. As a secondary mission, it provides airborne forward air control, guiding other aircraft against ground targets. A-10s used primarily in this role are designated OA-10. The A-10 is expected to be replaced in 2028 or later.

Criticism that the U.S. Air Force did not take close air support seriously prompted a few service members to seek a specialized attack aircraft. In the Vietnam War, large numbers of ground-attack aircraft were shot down by small arms, surface-to-air missiles, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. In addition, the UH-1 Iroquois and AH-1 Cobra helicopters of the day, which USAF commanders had said should handle close air support, were ill-suited for use against armor, carrying only anti-personnel machine guns and unguided rockets meant for soft targets. Fast jets such as the F-100 Super Sabre, F-105 Thunderchief and F-4 Phantom II proved for the most part to be ineffective for close air support. The A-1 Skyraider was the USAF’s primary close air support aircraft.